#include <stdio.h>
#include <math.h>
#include <stdlib.h>

unsigned int SDBMHash(char *str)
{
  unsigned int hash = 0;
 
  while (*str)
    {
      // equivalent to: hash = 65599*hash + (*str++);
      hash = (*str++) + (hash << 6) + (hash << 16) - hash;
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// RS Hash 
unsigned int RSHash(char *str)
{
  unsigned int b = 378551;
  unsigned int a = 63689;
  unsigned int hash = 0;
 
  while (*str)
    {
      hash = hash * a + (*str++);
      a *= b;
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// JS Hash 
unsigned int JSHash(char *str)
{
  unsigned int hash = 1315423911;
 
  while (*str)
    {
      hash ^= ((hash << 5) + (*str++) + (hash >> 2));
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// P. J. Weinberger Hash 
unsigned int PJWHash(char *str)
{
  unsigned int BitsInUnignedInt = (unsigned int)(sizeof(unsigned int) * 8);
  unsigned int ThreeQuarters	= (unsigned int)((BitsInUnignedInt  * 3) / 4);
  unsigned int OneEighth = (unsigned int)(BitsInUnignedInt / 8);
  unsigned int HighBits = (unsigned int)(0xFFFFFFFF) << (BitsInUnignedInt 

                                                         - OneEighth);
  unsigned int hash	= 0;
  unsigned int test	= 0;
 
  while (*str)
    {
      hash = (hash << OneEighth) + (*str++);
      if ((test = hash & HighBits) != 0)
        {
          hash = ((hash ^ (test >> ThreeQuarters)) & (~HighBits));
        }
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// ELF Hash 
unsigned int ELFHash(char *str)
{
  unsigned int hash = 0;
  unsigned int x	= 0;
 
  while (*str)
    {
      hash = (hash << 4) + (*str++);
      if ((x = hash & 0xF0000000L) != 0)
        {
          hash ^= (x >> 24);
          hash &= ~x;
        }
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// BKDR Hash 
unsigned int BKDRHash(char *str)
{
  unsigned int seed = 131; // 31 131 1313 13131 131313 etc..
  unsigned int hash = 0;
 
  while (*str)
    {
      hash = hash * seed + (*str++);
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// DJB Hash 
unsigned int DJBHash(char *str)
{
  unsigned int hash = 5381;
 
  while (*str)
    {
      hash += (hash << 5) + (*str++);
    }
 
  return (hash & 0x7FFFFFFF);
}
 
// AP Hash 
unsigned int APHash(char *str)
{
  unsigned int hash = 0;
  int i;
 
  for (i=0; *str; i++)
    {
      if ((i & 1) == 0)
        {
          hash ^= ((hash << 7) ^ (*str++) ^ (hash >> 3));
        }
      else
        {
          hash ^= (~((hash << 11) ^ (*str++) ^ (hash >> 5)));
        }
    }
 
  return (hash & 0x7FFFFFFF);
}


static unsigned int calc_hash(const unsigned char *strx,
                              unsigned int len)
{
  unsigned int n = len;
  unsigned int r = 0;
#define HASHSTEP(r,c) ((r)*67 + ((c) - 113));
  while(n--)
    r = HASHSTEP(r,*strx++);
  return r + len;
#undef HASHSTEP  
}
